There's a category of art - looked down upon by most artists - known as 'chocolate box art' - which denotes the sort of overly sentimental, overtly nostaligic view of the countryside etc... You may want to familiarise yourself with the category, because the world you're seeking to create is indeed a bit 'chocolate box' - so use the associations knowingly:

http://en.wikipedia.org/wiki/Chocolate_box_art

As expressed, your little girl is going to be clever balance of 'adorable' and 'spunky' - and I think the too-wide-eyed approach could make her too 'passive' and girly-wirly - it will be an issue of balance, but here are some additional references that may help clarify her still further: